Over 4000 years ago, nomads sprung from the soil of northeastern Europe and entered the Indus Valley of ancient India. They called themselves Aryans, or noble ones, and the religion they brought with them comprised the first practice of Hinduism. The centerpiece of Aryan religion was a fire sacrifice to the gods performed by priests specially trained to chant sacred hymns. The hymns themselves were known as Vedas or sacred knowledge. The Vedas are the scriptural bedrock of the Hindu tradition.